MOORE, Okla. (AP) — Rescue crews are working through the night after a monstrous tornado barreled through the Oklahoma City suburbs, demolishing an elementary school and reducing homes to piles of splintered wood.

Officials say at least 51 people were killed in Monday’s twister, including at least 20 children. Those numbers were expected to climb.

The center of the devastation is in Moore, a community of 41,000 people 10 miles south of Oklahoma City.

More than 120 people were being treated at hospitals, including about 50 children. Amy Elliott, spokeswoman for the Oklahoma Medical Examiner’s Office, said Tuesday that there could be as many as 40 more fatalities from Monday’s tornado.